How to make a Mazda MX-5 Miata ND competitive in C Street

J.A.
By J.A. Ackley
Mar 27, 2024 | Mazda, Miata, Autocross, MX-5, Mazda Miata, Mazda MX-5, ND, Good-Win Racing, Brian Goodwin | Posted in Buyer's Guides | Never miss an article

Photography Credit: Rupert Berrington

The Mazda MX-5 Miata ND (2016–present) is one of the most popular cars in autocross competition, especially SCCA C Street (we’ll cover STR in a future story), and with good reason. It’s nimble, responsive and, most importantly, quick, straight off the lot.

However, you can always make something better. We asked Brian Goodwin, of Good-Win Racing, for his …

This content is available for GRM+ members and Grassroots Motorsports magazine subscribers only.

You can read it for free in 163 days or subscribe to GRM+ to read right now.

Subscribe now

Already a member?

Login to read

Join Free Join our community to easily find more Mazda, Miata, Autocross, MX-5, Mazda Miata, Mazda MX-5, ND, Good-Win Racing and Brian Goodwin articles.
Comments
maschinenbau
maschinenbau GRM+ Memberand UberDork
10/12/22 9:55 a.m.

Because they’re a twin-tube shock, we’ll leave them at lower pressure than the stock monotubes. The car will sit a little bit lower and you’ll pick up a little negative camber, even though the length for the Koni Sport shocks is the same as the stock ones.

To me this goes against the intent of Street class rules. It's an open secret that certain aftermarket shocks lower the car, even though *supposedly* the spring perch locations are dimensionally correct. It is not insignificant either...about an inch, picking up at least a 1/2 degree of camber. The best racecar alignment shop in Atlanta can only get me -1.2 at all 4 corners meanwhile the same car, same year, same color, but on Konis is at -1.8 according to the owner. The difference is really obvious when were parked together in grid. But I guess that's racing. Sincerely - a slow complainer :) 

David S. Wallens
David S. Wallens Editorial Director
10/12/22 10:57 a.m.

I've had that very discussion with someone a bit high up in the Solo community: ride height isn't protestable yet spring perch height is. 

dps214
dps214 Dork
10/12/22 11:46 a.m.
maschinenbau said:

Because they’re a twin-tube shock, we’ll leave them at lower pressure than the stock monotubes. The car will sit a little bit lower and you’ll pick up a little negative camber, even though the length for the Koni Sport shocks is the same as the stock ones.

To me this goes against the intent of Street class rules. It's an open secret that certain aftermarket shocks lower the car, even though *supposedly* the spring perch locations are dimensionally correct. It is not insignificant either...about an inch, picking up at least a 1/2 degree of camber. The best racecar alignment shop in Atlanta can only get me -1.2 at all 4 corners meanwhile the same car, same year, same color, but on Konis is at -1.8 according to the owner. The difference is really obvious when were parked together in grid. But I guess that's racing. Sincerely - a slow complainer :) 

It's specifically written in the rules that shocks are allowed to affect ride height. Considering manufacturing tolerances, option packages, tire size differences, etc, good luck enforcing anything else anyway.

maschinenbau
maschinenbau GRM+ Memberand UberDork
10/12/22 12:39 p.m.

I get why in theory it's allowed. To accommodate true "street" cars, they have to allow for aftermarket options so owners can maintain their cars for years to come without relying only on OEM parts supply (Rockauto, Advance, etc). This allowance accommodates all sorts of practical options, and their differences in tolerances and option packages, but also opens the door of opportunity for performance companies to sell pricey products that have a targeted advantage. So the only 2 options the rulemakers have are 1.) mandate OEM factory shocks only or 2.) allow all aftermarket shocks.

So I totally understand it. It just sucks that you have to drop $1k on shocks in addition to 200tw "street" tires to be competitive in the closest thing to a stock class. I guess that's why it's called "Street" not "Stock".

dps214
dps214 Dork
10/12/22 1:05 p.m.

The funny thing is a very similar conversation has been going on on another forum, except there's another zero in the damper cost figure (okay, realistically it's like $5k). I do sympathize, and I think it's a little ridiculous that there's zero functional restrictions other than being limited to two adjusters. But gas pressure and the resultant ride height effects are always going to have to be open unless you're only allowing OE dampers. And even then, replacement OE dampers are very often not exactly identical to the actual original parts, so they could still end up not being fully compliant.

ConeKiller1
ConeKiller1
10/12/22 11:20 p.m.

Don't forget you need really cool graphics... they really help the car go faster :)

badair
badair New Reader
10/13/22 12:07 a.m.

My setup is the same.

I found that cutting an inch off the front bumpstops wasn't enough for me. I took another 0.25 inch off and now the balance is tolerable (but still pushy).

I notice that with the Karcepts bar where I like it for steady-state balance, and with the front Konis on full soft, the front seems way too floppy during the fastest transitions -- delayed reaction followed by an upsetting bounce. I was happier last event when I went up to 1.25 turns from full soft between runs, although I'm not sure that's in the range of the valve where it really matters so maybe it was placebo and increased caution on course. I'll continue experimenting.

Zink11
Zink11 GRM+ Memberand New Reader
3/29/24 3:42 p.m.

I thought all you had to do to make an ND MX-5 competitive in CS was to buy one!    

2003 Honda S2000 owner. 

You'll need to log in to post.

Our Preferred Partners
Gq3XGzl0nHnxkmPIY1Vm3IMj3xU9qgP69flDw9EVRY6R1We7qmb7UygqufpbbSNh